Funding for this research was provided by:
International Max Planck Research School for Organismal Biology
Max Planck Institute for Ornithology (MPIO)
Received: 4 May 2021
Accepted: 25 July 2021
First Online: 5 August 2021
: All experimental procedures were conducted according to the legal requirements in Germany and were approved by the governmental authorities of Oberbayern, Germany.
: Not applicable.
: The authors declare that they have no competing interests.